Background: Animal welfare encompasses both its physical and mental states. This latter could be altered by several psychological-related disorders including stress and anxiety. To address these issues, Melissa officinalis, a Lamiaceae plant, ensuring the anxiolytic-type effects, is widely used. In this study, the main aim was to explore the effect of a commercial hydro-alcoholic Melissa officinalis extract (MOE) and its major compound rosmarinic acid (RA) on dogs’ behavior and metabolome. To do so, twenty healthy beagle dogs were randomly assigned to 4 dietary supplements (5 dogs/group): the first group received a placebo supplemented with maltodextrose (200 mg/kg), the second group was supplemented with MOE (200 mg/kg), the third group received RA at a dose of 10.6 mg/kg, and the fourth group was administered α-casozepine (AC) at a dose of 225 mg in capsule form. Dogs’ behavior was monitored after 4 weeks of treatment using a standardized evaluation grid developed by Oniris. In addition, 4-hydroxybyturic acid (GHB) was quantified to study the effect of the supplementations on the metabolites of γ-aminobutyric acid (GABA) biosynthetic pathway. Moreover, the impact of all supplementations on dogs’ metabolome was assessed using untargeted metabolomics at the end of the supplementation period. Results: Results demonstrated significant differences between the mean behavioral score of placebo group (-3.4) compared to MOE (2.0), RA (1.4), and AC (0.8) groups. In addition, GHB measurement revealed a decrease in its quantity in all supplemented groups compared to the control. Moreover, untargeted metabolomics uncovered several metabolic pathways, that were impacted by MOE supplementation linked to lipids and bile acids metabolism. Furthermore, RA supplementation impacted fatty acids and lipids metabolism pathways while supplementation with AC affected pathways linked to lysine and sphingolipids metabolism. Conclusions: Our study demonstrated a calming effect of MOE on beagles and proposes a novel hypothesis that sheds new light on its potential mechanism of action. This study underlines metabolomics as an effective tool for gaining deep insights into the metabolic changes associated with supplementation.

In laying hens, maintaining optimal bone health and development from the early stages is crucial, as it directly affects their egg-laying efficiency, overall welfare and productivity. Studies have shown that grape polyphenols from Vitis vinifera enhance bone health in both humans and animals. Still, the mechanisms behind this effect remain unclear, given the diversity of grape polyphenols and their varying mechanisms of action. The objective of this study was to investigate the effect of a standardized dry grape extract (SDGE) on bone quality and metabolome of future laying hens reared in commercial conditions. Therefore, 36300 day-old pullets were randomly divided into two barns on the same farm site. Both received the same diet, with the addition of 30 mg/kg of SDGE (Nor-Grape®, Nor-Feed, France) from day 1 until week 17 in the supplemented group (SDGE). At the end of the supplementation period, several bone quality parameters were analyzed on 50 individuals per group. Additionally, non-targeted metabolomics on plasma and bones were performed to uncover the impact of SDGE supplementation on pullet's metabolome. Results demonstrated that keel bone deformity tended to improve following SDGE supplementation (P = 0.10). Moreover, SDGE intake significantly increased bone dry and mineral content, compared to the control group (P < 0.05) and tended to increase calcium (Ca) (P = 0.074) and phosphorus (P) content (P = 0.055). On the other hand, non-targeted metabolomics on plasma samples revealed an impact on fatty acids and glycerophospholipid metabolisms while bone samples analysis uncovered pathways related to sphingolipid and estrogen mediated signaling pathways. Overall, this study suggests novel mechanisms related to estrogen signaling through lipid metabolism in SDGE supplemented pullets and highlights that nutritional intervention with SDGE in early developmental stage of future laying hens improves their bone health prior to entry into the laying phase, thus proving a useful tool in bone health management.

While our group previously demonstrated the calming effects of Melissa officinalis extract (MOE) in dogs, the underlying brain-level mechanisms remain unclear. To address this, we investigated these mechanisms in rats using an untargeted metabolomics approach. Twenty-four male Wistar rats were divided into three groups (eight rats per group): control (standard diet, SD), a group fed a high-fat high-sucrose diet (HFHSD), and HFHSD administrated with a hydro-alcoholic standardized MOE (HFHSD MOE) at a dose of 200 mg/kg. Body weight, behavior through elevated plus maze (EPM), and glucose tolerance using the oral glucose tolerance test (OGTT) were monitored. After 12 weeks of supplementation, plasma and brain metabolomes were explored using non-targeted metabolomics. Although the EPM revealed no significant behavioral improvement, the OGTT showed a significant reduction in blood glucose area under the curve (AUC, p < 0.05), suggesting a metabolic effect of MOE. Metabolomic analysis highlighted two key pathways: (1) bile acid biosynthesis in plasma, as previously observed in our dog study, and (2) pentose phosphate metabolism in the brain. These results provide insight into central and peripheral mechanisms influenced by MOE and generate hypotheses on pathways potentially linked to previously reported behavioral effects in dogs, offering targets for nutritional interventions.